I was stung by a large jellyfish and the pain still persists after a few hours. Help needed.
I swam with my newly-met friend in my home town (Tuen Mun, Hong Kong). About 45 minutes into my swim I hit a large brown jellyfish with long tentacles (more than a metre). The water was brown and murky so I couldn't avoid it and hit it with half of my body, including my lips, my right arm, under my right armpit and my right ankles, and also a bit of my left forearm. The pain was so intense so I nearly wanted to cry and my form was seriously affected. Luckily my friend was much slower than me so we could still stay together.
I could only concentrate back in my form after around an hour but the pain still persisted. I got out of the water about 1.5 hours afterwards and got home and I'm still feeling intolerable pain. I have applied white vinegar and the pain still persists till now. It's now about 3.5 hours after the sting and I still can't concentrate my mind. There are no other ill effects except intense pain and swollen skin.
Normally in this season I swim with increased coverage, but last week I found my swimsuit too small and it chafed my nipples so I returned to standard channel swimsuit today and the worst thing happened to me. The last time I was stung by such a large jellyfish was about 3-4 years ago with the same intense pain. Now I'm really scared.
A Google search using the description suggest that the jellyfish may be the dreaded Lion's Mane, and the pictures confirm the suggestion. There are also articles about Lion's Manes appearing in Hong Kong by including the government but the Wikipedia article says it only appears in cool water (which Hong Kong isn't). What species do you think I was stung by, which is large, brown, with tentacles over a metre? What should I do now to mitigate the pain?
Also I'm now really scared. I can confidently say that 2 such stings can end any channel swim for me because the pain is intolerable. How can I avoid them?